1. Field of the Invention
The invention generally relates to voltage reference circuits and, more particularly, to voltage regulators capable of fast shutdown.
2. Description of the Related Art
Precision voltage reference circuits are critical elements of various devices, systems and equipment, such as portable devices, instrumentation and test equipment, data acquisition systems, medical equipment, servo systems, and the like. Voltage reference circuits are used to supply a steady and reliable voltage reference to other circuits or systems. Similarly, low drop-out voltage (LDO) regulators are also used to provide regulated voltages in a precise and reliable manner. Generally, in order to ensure that power supply is shutdown rapidly without negatively influencing the devices, systems or equipment, a fast shutdown device is required to perform a fast shutdown. However, for conventional LDO regulators, an electrostatic discharge (ESD) device with a large area is required to protect fast shutdown devices. In addition, the fast shutdown devices would become a bottleneck of ESD performance.